This invention concerns a system for broadcasting radio and/or television programs, and receiver apparatus and devices compatible with this system. The broadcasting system transmits digital data, in addition to analog program information. Consequently, the system and associated receiving devices are characterized presently by the term "data radio".
In today's radio broadcasting environment, mobile receivers of broadcast programs (e.g. radios used in cars and trucks, and TV sets used in motor homes), are manually set by their users to a desired program channel (or station) served by a single transmission tower, and remain tuned to that channel until transmitted signals are no longer receivable with clarity. At that point, the user can either turn the receiver off or tune it to another program channel which typically would originate from a different source and contain program matter different from what was previously being received. This is both an unnecessary distraction for operators of vehicles containing such receivers, and tends to negatively affect commercial interests of disseminators of such programs by unduly limiting the geographic range of their transmissions.
This environment is based upon and derives from the earliest and most primitive forms of radio broadcast transmission, wherein a program carried on a single frequency spectrum could be received over a large geographic region restricted only by the power of transmitters and the sensitivity of receivers. Thus, a broadcast transmission station supported by commercial advertising would generally transmit commercial program materials having general geographic relevance rather than locale-specific relevance; e.g. advertisements specific to a product sold throughout the broadcast region, or a commercial establishment having many outlets in the region, rather than advertisements specific to a business enterprise operating in a specific locale constituting a small portion of the region.
However, we observe presently that the recent evolution of cellular telephone technologies, wherein a large geographic region is divided into multiple smaller regions served by separate cellular transmitters, provides a convenient basis for enabling radio program broadcasters to substantially expand their regions of operation, by reusing allotted frequency spectra in non-adjacent "cellular" locales, and this togetherwith othertechniques presently contemplated and described herein could lead to delivery of unique services to receivers of such programs and also create unique new business opportunities for respective broadcasters.